My R51 (2006, V6 Petrol) is running a little rough ultimately, like if 1 or 2 cylinders are failing.
A little backstory: A while ago this issue started, and happened only after some time with the car running, when it reaches the working temperature. My first thought was to blame the spark plugs, so I changed them. In fact, a trusty mechanic did it.
It did not worked.
The mechanic suspected of the fuel injection system, because it was not throwing any codes, so we discarded the coils. So, he took all injectors off, 3 were declared dead and replaced and the remaining ones were cleaned and all of them equalized.
It did not worked. In fact the problem only got worse.
Then we discovered that the cats were clogged. Not so unsual for a 15 year old car running on brazilian E25. Fixed that. Also changed the fuel pump and some hoses and fuel tank was cleaned.
Still, it is not working totally fine. Sometimes in idle, like when stopped at traffic light, I feel it suddenly working fine, as if the issue has disapeared, to come back 1 or 2 minutes later. Sometimes it works fine.
I ran out of ideas, actually.
Anyone has exeprienced something like that? Any help is appreciated.